Apparatus for producing pressure-tight tube and tube seat connections



Aug. 29, 1944. c. A. MAXWELL APPARATUS FOR PRODUCING PRESSURE-TIGHT TUBE AND TUBE SEAT CONNECTIONS Original Filed May 20, 1959 5 Sheets-Sheet 1 sis.)92 3.- k

INVENTOR. Car] A.Maxwe// A izforney Aug. 29, 1944. c MAXWELL APPARATUS FOR PRODUCING PLESSURE-TIGHT T-UBE AND TUBE SEAT CONNECTIONS 5 Sheets-Sheet 2 Original Filed May 20. 1939 INVENTOR. Car] Maxwell A iior-fley c. A. MAXWELL 2,357,123

APPARATUS FOR PRODUCING PRESSURE-TIGHT TUBE AND TUBE SEAT CONNECTIONS Original Filed May 20; 1939 5 Sheets-Sheet 3 v INVENTOR. Carl A Maxwell 14 Aiforney Aug. 29, 194 c. A. MAXWELL APPARATUS FOR PRODUCING PRESSURE-TIGHT TUBE AND TUBE SEAT CONNECTIONS Original Filed May 20, 1939 5 Sheets-Sheet 4 vi 2;! 2/ A a??? o 7 2., U

Carl A. M53523 Attorney "Au 29, 1944. A, MAXWELL 2,357,123

APPARATUS FOR PRODUCING PRESSURE-TIGHT TUBE AND TUBE SEAT CONNECTIONS Original Filed May 20, 1939 5 Sheets-Sheet 5 INVENTOR.

Carl AMaXWe/l Aiiorney Patented Aug. 29, 1944 2,357,123

UNITED. STATES PATENT OFFICE- f 2,357,123 p I APPARATUS FOR PRODUCING rmissrmn- 'TIGHTTUBE AND TUBE SEAT CONNEC- 'TIONS v I v 1 Carl A. Maxwell, Akron, Ohio, asslz nor -i-to The Babcock & Wilcox'Company, Newark, N. 1., a corporation of New Jersey Original Application my 20, 1939, SerialNo. 274,149. Dividedand this application May as,

1941, Serial No. 394,758

6 Claims. (Cl. 153 80.5)

The improvements with which this invention is concerned. relate to devicestin which expanded tube seat connections are employed. The invention involves novel apparatus ior. carryingout a novel method of making such connections. 1

It is anobject of the invention to produce pressure-tight tube seat connections without imposing undesirable residual stresses upon theoperative parts of thetube employed. For example, the invention may be employed to advantage in fluid'heat exchange apparatus of the convection type wherein a pluralityof spaced tubes are fixed to one drum wall or tube sheet at their inletends, and to another drum wallortube sheet at their outlet ends. The, tubes normally conduct one heat exchange fluid through another at a differ:

ent temperature and the operatingtemperatures and pressures areoften of high degree. Among other objects ofthe invention is the production of apressure-tight expanded tube seat connection in a manner which will not involve the high degree of skill involved with roller ex: panding. I

It is also an'object of the invention to provide an expandedjoint whichcan be produced with great rapidity: This contributes materially to the j reductionof the cost of any installation in which the illustrative method is employed.

The invention involves such operations that portions of a tube 'wall throughout the length of the tube seat are subjected to the same'predetermined working and the tube stressing is con fined to the tube length within the tube seat.

When theinvention is employed in the manufacture .of the; above indicated apparatu the tubes are uniformly secured to the tube sheets,

or drum walls in pressure-tight relationship, and

the main portions of the tubes are not bowed by longitudinal compression stresses. Furthermore, none of the tubes in their unsupported length are The invention will be described with reference to the accompanying drawings, in which:

Fig. 1 is a view showlnglthe' tube'expander in elevation with the tube sheetand the associated tube shown in section; t

Fig. 2 is a viewsirhilarfltoFig. 1 showing the position of the expander while it is moving in the pander head at the end of the sleeve shown in operator, This figure also illustrates the first step in the expanding method, the expander head being inserted within the tube to be expanded;

Fig. 7 is a longitudinal section of the Fig. 6 apparatus. illustrating the initial expanding of the tube by the action of the hydraulic operator upon theadjacent expanding rings;

Fig 8 is a transverse section taken on the line 8-8 of Fig. 6, looking inthe direction of the arrows; v

Fig. 9 is a transverse section taken on the line 9--9 of-Fig. I, looking in the direction of the arrows; 1 1 a Fig. 10 is a longitudinal section of the Fi 6 apparatus illustrating the conditions substantial- 1y at; the completion of the tube expandin operation;

Fig. 11 is a longitudinal section through the hydraulic operator illustrating the movement of fluid to effect the reverse movement of the expander head; t

Fig. 12 is a detail longitudinal section of a part or the piston construction within the hydraulic operatonp t Fig. 13 is a partial transverse section taken I .along the plane indicated by the line 13-13 of Fig; 12 and looking in the direction of the arrows: and

Fig. 14 is a diagrammatic view illustrating the expanded connections-will be pressure-tight.

. '40 putin compression by the expanding operations.

- Fig. 3of the drawings clearly snows the relationship of the parts constituting the tube expander. It includes the mandrel 10 upon which the. expander sleeve I2 is slidably mounted. The annular end of the sleeveli i screw-threaded into a collar II which is preferably of greater diameter than the tube Ii into which the sleeve and H the mandrel are inserted prior to the initiation of the expanding operation. This collar may be formed in two halves so as to facilitate the replacement of the sleeve II. The collar acts as a stop totdetermine the depth of the expanding and his formed at one end witha recess I! to receive the end of the tube l6 which may project through the wall 28 initially, or as the result of the expending action.

The intermediate portion of the mandrel ll such as the portion AB may be of cylindrical contour and of such diameter that the sleeve I2 is freely slidable thereon, but the section AC is tapered so that it increases in diameter away from the position A. Thus, after the expander is inserted in the tube 16, as indicated in Fig 1 of the drawings, relative transitory motion/between the mandrel I and the split ball expander head causes the segments 2l24, inclusive, of the expander head to move radially and outwardly so as to expand a portionof the tube with a metal drawing action and cause it to be fitted tightly in the tube seat, as indicated in Fig. 2 of the drawings. The external surfaces of the head segments approximate spherical surfaces so i as to facilitate such action.

When a pneumatic tool, such as that indicated at 28 in Fig. 3, exerts a pull to the'right on the.

coupling 30 (screw-threaded upon the righthand end of the mandrel as shown) the tapered section AC of the mandrel is moved through the' expander head 20 to cause this expanding action, and the degree of expanding of the tube when the extended had bears against it is determined by the position of the adjusting nut 32 upon the opposite end of the mandrel. As the mandrel is pulled to the right by the tool 28 the end surfaces of the segments of the expander head 20 abut against .the right-hand end of the adjusting nut 32, and further movement of the mandrel to the right draws the expander head through the tube and expands the tube within the tube seat formed in'the tube sheet 26. The adjusting nut 32is'held in a predetermined position upon the mandrel ID by a lock nut 34. This construction permits compensation for slight variations in internal dimensions, or bore of the'head 2.0

at its position of bearing on the tapered mandrel portion. I i

The expandersleeveis preferably formed; of tool steel and it is hardened and drawn from the back for spring action. There are longitudinal segments such as those indicated at 36 and .38 in-Fig. ,4 extending from the screw-threaded annular portion to the expander head segments 2|-24, which are hardened and ground;

tosize, the former segments being formed by splitting the sleeve along longitudinal lines" as expander head segments are biased by the spring 1 action of the segments 35 and 38 ,etc., inwardly to, a position wherein theoutside diameter of the entire expander head islessthan the inside diameter of the tube I6; This permit's'the expander to be readily inserted within the tube a as indicated in Fig. I-of the drawings. Also, the diagonal or oblique spilts between the segments ll-24, inclusive,.provides for substantially uni-, form expanding action throughout the entirecircumference of the tube l6.

It is to be understood thatthe tool 28 for op- It is also to be understood that the tube sheet 26 may be illustrative of a wall of a drum or header used in the construction of a heat exchanger wherein two drums are directly connected by a plurality of. tubes. The method of forming'tube seat connections described herein is particularly advantageous in the construction of such heat exchangers, inasmuch as it eliminates the undesirable effect of working the metal at the expanded locations so that there is an actual lengthening of the tubes between the drums or headers. The illustrative method avoids the residualstresses on the tubes and the tube'seats imposed by such lengthening of the tubesl Theillustrativemethod involves the limiting oi-the initial expanding action to a position remote from a tube end and adjacent the outer r in the illustrative method, there may be such elongations of the tubes that adjacent tubes and tube seats will be left in a state of high residual stress, or the tubes themselves may be actually bowed by the compression stresses imposed. Such effects can not take place when the illustrative method is employed.

. The above described expander is particularly adapted to form a component part of the system indicated in Fig. 14 of the drawings and it is well adapted to be actuated by the fluid pressure operator indicated in Figs. 6-13, inclusive. This operator'is illustrated as associated with a modified form 'of the expander head but it will be appreciated from the following description that it may be equally well applied to the expander' upon which a sleeve 66 for an inner piston is telescopically mounted. The inner piston 88 has sliding movement .within the outer piston and the sleeve likewise may have movement relative erating' the. expander. is merely. representative and that ,theexpander may be operated by any suitable mechanism for exerting the required pull. The tool 28, ,as' shown, 'is provided with the screw-threaded socket for receiving the end of the coupling 30., This coupling is held Y in position with reference to the tool 28 by a nut 52 which is in turn screw-threaded to receive the socket 58. The tool 28 may be a pneumatic air hammer or any other suitable motor operated mechanism for exerting the requiredpullon the expander.

to the mandrel; The sleeve may thus be said to form a bearing for the mandrel and the com bined sleeve and mandrel unit may slide within a stufiingbox IO-and the packing 12 secured within one endof the cylinder,

The other end of the cylinder is closed by a cap 14 provided with a stufling box 18 in which a hollow piston rod 18 for the main piston has sliding movement. A fluid pressure line is connected to the hollow piston in order to provide for pulling the expanderhead out of the tube which is being expanded. During this action thefiuid flows from the cylinder through a fluid pressure connection 82 which is arranged radially with respect to this cylinder andconnected in a head including the mandrel and the expander rings may be freelyinserted within the tube to be expanded with the end of the tube abutting against a reaction shoulder 90 formed in the stuffing box I at the end of the cylinder 60.

The expander rings 84 and 86 are constructed of spring steel and the openings between their facing ends are offset as indicated in Figs. 6 and '7 of the drawings. It will also be noted in connection with this disclosure that the expansion of the rings is indicated by the increase in the size of the openings.

To initiate the expanding of the tube the control switch 92 (see Fig. 14) is operated to-start the motor 94 and the pump 96 so as to force fluid through the inlet 98 at the end of the hollow piston rod I8. The fluid flows from this piston rod through radial ducts I00 and I02 and then through horizontal ducts I04 and I06 formed in the piston rod and communicating with a chamber I08 between the right-hand head of the main piston and the inner piston 68. The inner piston 68 can not move to the left on account of the presence of the pins IIOI I2 which are secured to the inner piston in such a way that they extend through openings in the left-hand head N4 of the outer piston and abut against the left-hand end of the cylinder 60. Therefore, the main piston 62 moves to the right and the parts are brought into the positions indicated in Fig. '7' of the drawings. During this action the tapered or frusto-conical portion 08 of the mandrel 64 is pulled through the expanding rings so that the adjustable stop II 6 screw-threaded on the end of the mandrel contacts with the expander ring 84 and limits the expansion of both rings. This action causes the expansion of a portion of the tube near the inner face of the metallic wall H8 in which the tube seats are formed. This expansion is clearly indicated in Fig. 7 of the drawings at I2 I.

During this initial expandin operation the main piston 62 may be said to slide along the pins 4 IIO--I I2 fixed to the inner piston and this action continues until the parts reach the positions indicated in Fig. 7 wherein the left-hand head II4 of the outer piston contacts with the inner piston. At this time the longitudinal ducts I20 in the outer piston 62 (see Figs. 6, 7, and 8) are moved so that their inlet ends are brought into communication with the chamber I08 between the inner piston and the right-hand head of the outer piston. Thereupon, the fluid flowing from the pump 94 and through the hollow piston rod 18 flows into the chamber I22 which is clearly indicated at the left-hand side of the outer piston in Fig. 7 of the drawings.

Continued flow of the fluid through the longitudinal main piston ducts I20 into the chamber I22 causes both pistons, the mandrel, and the expander rings, to move as a unit, the pistons moving toward the right-hand end of the cylinder and the expander rings being pulled through the tube I24 to the-end of thetube seat. The expanding operation is thus completed and the switch 92 controlling the inflow of fluid to the under pressure then flows through the radial inlet I32 into the chamber I34 at the right of the main piston. This action forces the entire-piston'assembly to the left and the flow of fluid from the chamber I22 through the longitudinal main piston ducts I and through the hollowpiston I8 isreversed as indicated by the arrows in Fig. 11. This movement continues until the outer '(lefthand) ends of the pins I I0-I I2 contact with the left-hand end wall of the cylinder. Then, the movement of the inner piston to the left is stopped and continued movement of the main piston to'the left interrupts the communication between the ducts I20. and the chamber I08 between the two pistons so that continued movement of the main piston 62 to the left is permitted only when some means of egress'for the fluid entrapped in the chamber I22 is provided. Such egress-can take place through ducts I40" formed in the left-hand head II4 of the main piston. These ducts communicate with an annular chamber I42 formed-in the left-hand'face of the inner piston as indicated in' Figs 11 and 1-2 of the drawings. Fig. 12 shows one of these ducts above the inner piston pin III and communicating with a circular chamber I44"in.which there is'located a valve-closing spring I46 surrounding thestem I48 of the poppet valve I50 andconfined between the inner piston and an annular locking member I52 on the valve stem. Each chamber I44 in which a valve spring is located communicates with an annular chamber I54 immediately at the/ base of the valve by means of ducts I56 which are parallel to the valve stem. The arrangement of these ducts is particularly indicated in Figs.;12 and 13 of the drawings. 1

With the elements arranged as above indicated. continued movement of the fluid against the main piston 62 in the direction of the arrows of Fig. 11 compresses the fluid within the chamber I22 and causes it to flow through-the ducts I40, and I56 to open the poppet valves. The fluid thenflows toward the hollow piston rod I8 of the main piston and thence into the closed'fluid circuit, this movement continuinguntilthe mandrel is moved to the left-hand limit of its path of operation and the various parts of the expanderapparatus are brought to their starting positions which are indicated in Fig. 6 of the drawings; Thereupon, the expander head is moved to another tube to be expanded and the entire cycle of operations is repeated.

Fig. 14 indicates a, system employing the above described expander apparatus, and operative to expand the tubes communicating with a pressure vessel such as a drum. The operator, within'the drum, moves the double acting cylinder '60 so that the expander head is disposed in'or'ierative po; sition in a tube end and closes th expanding switch 92. This action operates through a solenoid- I60 to actuate the four-way valve I62 and start the motor 94 and pump 86 in such operation that the fluid flows through the pressure line I64 axially connected to the cylinder 60 and connected to thehollow piston I8. The pump creates enough pressure in this line to pull the expander head through that portion of the tube within the tube seat in the drum wall I66 and the pressure required to effect this operation may be measured by a pressure gageIGIl in direct communicatibn with the piston chamber of the expandercylinder. and arranged so that it may be conveniently read .by theoperator. The .pressures employed in the succeeding expanding operations may also be measured and recorded by a recording pressure gage II0 which is in communication with the line I64. This recording pressure gage affords a visual comparison of the pressures required to perform the successive expanding operations and when the pressure required is a measure of the tightness of the tube the flow through the four-way switch I62 by theenergizing of an opposed solenoid I12. This solenoid has as its armature or core the switch rod I'll connected by the link I16 with the stem I". This solenoid is also in series with a circuit which starts the operation of the pump 94 forcing the fluid through the return line I80 to the radial inlet I32 of the expander cylinder and continues such flow until the parts of the expander are brought to their starting positions. Thereupon, the return switch I30 is opened.

The motor and pump unit is particularly designed to meet the requirements of hydraulic installations which call for a pump automatically providing high operating pressures as they are required in the work to be done. The assembly includes a low pressure pump and a high pressure pump directly connected to the shaft I86 of the driving motor 94, and above the pump there is a relief valve I88, a check valve I90, and a bypass valve I92 arranged from left to right inthe order named. In Fig. 14 the inlet for both the high pressure and low pressure pumps is at the bottom and a pressure line I94 is indicated as extending from the valve assembly directly to the four-way valve I62 which controls the movement of the fluid in the lines connected with the expander.

The method effected by the described apparatu's includes the employment of a fluid successively brought up to the pressure requirement for effecting separate and successive tube expanding operations on tubes in the same tube sheet or drum wall, involving the determination of minimum pressure necessary to produce a connection which will be pressure-tight under predetermined operating conditions, the measuring of the fluid pressures for the successive expanding operations, adjusting of the expanding conditions of any one of such operations for which the fluid pressures indicated are below said minimum, and reexpanding the pertinent tube under said ad- Justed conditions to bring the fluid pressure for its expanding up to said minimum.

Although the invention has been illustrated and described with reference to tubes of circular cross section, the system and the apparatus involved may, by relatively minor alterations, be advantageously used to expand tubes which are not circular in cross section. This result cannot be secured with the rotary types of expanders of the prior art.

Whereas, the invention has been described with reference to certain particular embodiments indicated in the accompanying drawings, it is to be appreciated that the invention is not limited to all of the details thereof. The invention is rather to be taken as of a scope commensurate with the scope of the subjoined claims.

This application is a division of my co-pending application, Serial No. 274,749, filed May 20, 1939 (now Patent 2,275,451, dated March 10, 1942).

What is claimed is:

1. In apparatus for expanding and drawing portions of tubes fitted within tube seats formed in a metallic wall; an expander head adapted to be freely inserted in a tube and including a mandrel, a sleeve mounted on the mandrel so that there may be relative movement between the sleeve and the mandrel, the mandrel having near one end a tapered portion tapering upwardly toward that end, and a split ring slidably mounted upon the mandrel about its tapered portion and arranged to be temporarily held by said sleeve against movement longitudinally of the tube; means reacting against a fixed element to cause relative movement between the ring and said tapered mandrel portion so that the tube is expanded, said means also subsequently pulling the expanded ring through a portion of the tube while the ring and the mandrel are maintained in fixed tube expanding relationship; and an adjustable stop on the mandrel for.determining the extent to which the ring is expanded by the relative motion of the sleeve and the tapered por-- tion of the mandrel, said means being operatively connected to the mandrel opposite the end having said tapered portion.

2. In a pull type tube expanding and drawing tool for efiecting pressure tight connections between tubes and a wall prezenting tube seats in which the tubes are fitted, an expander head contractible to a'tube entering condition and including tube engaging components, a mandrel embraced by said components, the mandrel having a head expanding tapered portion effective upon the head components when the mandrel has longitudinal movement relative to the expander head, pulling means coupled to the mandrel and acting to pull the expanded head along a tube and toward its adjacent end, and expander head holding means operatively associated with the expander head and the pulling meansand holding the tube enclosed expander head against movement with the mandrel until the former has expanded the tube.

3. In a tube expander of the pull type, a combined segmental expander head and unitary sleeve adapted to be freely inserted within a tube in contracted condition, a mandrel extending through said expander head and sleeve and having its operating end extending from theadjacent end of the tube, the mandrel also having a portion tapering downwardly toward said operating end of the mandrel and toward the adjacent end of the tube in which the expander head is inserted, said tapered portion of the mandrel having a length greater than the thickness of said head longitudinally of the mandrel, means including said sleeve for temporarily holding the expander head against movement with the mandrel during a part of the movement of the latter outwardly of the tube, the. sleeve being thereafter movable with the mandrel, and a stop against which the expander head abuts in order to determine the amount of expansion of the tube and to transmit the force by which the combined expanded sleeve and head is withdrawn from the tube, the stop being secured to the mandrel adjacent the larger end of the tapered portion of the mandrel and extending radially therefrom to have a path of movement in which the expander head is disposed, the tapering portion being disposed intermediate the stop and the operating end of the mandrel.

4. In a tube expander of the pull type, a mandrel having a tapered portion progressively decreasing in diameter toward the operating end of the mandrel 'which normally extends be yond a tube to be expanded, an annular expander head structure mounted on the mandrel and adapted to expand an enclosing tube when the tapered mandrel portion is moved longi tudlnally relative thereto, the contracted expander head being freely insertibledn the end of a tube to be expanded, means temporarily holding the expander head within the tube and against movement with the mandrel during a part of the movement of the latter outwardly of the tube to cause its tapered portion to expand the head, at least a part of said means being movable conjointly with the mandrel subsequent to said holding action, I and a stop secured to the mandrel adjacent the larger end of the tapered portion so as to determine the degree of expansion of the tube and transmit translational movement of the mandrel to said structure to expand a portion of the tube, said tapered portion being disposed at a'position between said operating end of the'mandrel and said stop, said stopextending radially from the mandrel into a path of movement in which said annular structure is disposed.

5. In a tube expander of the pull type, an expander head having expansible split rings adapted to be freely insertlble within a tube when in contracted condition, a mandrel extending through said rings and having a coupling component near its outer end, the mandrel having a portion tapering downwardly toward the end of the tube in which the expander head is inserted, the tapered portion being disposed within said rings and having a length greater than the combined thickness 01' said rings, an

abuts in order to determine the amount of tube expansion and to transmit the force by which the expanded rings are withdrawn from the tube, the stop being disposed adjacent the larger end of said tapered portion, and means holding the expander head rings against movement with the mandrel during a part of the movemeat 01' the latter outwardly of the tube, at least a part of said 'last named means being movable conjointly with the mandrel subsequent to said welding action, the tapered portion of the mandrel being intermediate the stop and said coupling component.

6. In a tube drawing and expanding device of the pull type, a mandrel having a conical tapered portion progressively decreasing in diameter toward the mandrel end by which the expander is adapted to be pulled out of a tube,

an expander head including expansible spring elements mounted on the mandrel and adapted to expand an enclosing tube when the tapered mandrel portion is moved relative thereto, the contracted expander head being, adapted to be freely moved into a tube to be expanded, means holding the spring elements against movement with the mandrel during a part of its tube expanding movement outwardly of the tube, at least a part of said last named means being movable conjolntly with the mandrel during its movement subsequent to said holding action, and an adjustable stop secured to the mandrel ad- Jacent the larger end of the tapered portion so as to determine the degree of tube expansion and to transmit translational movement of the .e mandrel to the expander head, said stop member beingmovable relative to the tapered portion to render a selected part of said tapered portion inoperative to expand said spring elements.

- CARL A. MAXWELL. 

